Subject C13 TD is a cool tower defense game that will keep you on your toes. You need to defend your energy cores and protect them from the attack. In the Subject C13 TD game you will do this by using your different attack turrets and tower defense units. Stop the monsters from reaching your energy core and keep your tower defenses and turrets at full strength by keeping them upgraded. It won"t be easy but if you have a good tower defense strategy you can survive the hordes of attacking monsters in Subject C13 TD.